Residual stress measurements in offshore wind monopile weldments using neutron diffraction technique and contour method

Jacob, Anaïs; Oliveira, Jéferson de; Mehmanparast, Ali; Hosseinzadeh, Foroogh; Kelleher, Joe; Berto, Filippo

doi:10.1016/j.tafmec.2018.06.001

Cited by 51 publications

(28 citation statements)

References 22 publications

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“…The strain-controlled cyclic test results showed that the load carrying capacity of the cross-weld specimen was comparable to that of the BM. Static test results in the literature 29 presented in Table 1 showed that the strengths of WM and HAZ were both slightly higher than the BM, but such behavior was not noticed in the cyclic test performed in this study. This can be explained by the cyclic softening behavior (Figure 7) observed within the first 20 cycles in this study.…”

Section: Resultscontrasting

confidence: 48%

On the performance of monopile weldments under service loading conditions and fatigue damage prediction

Biswal

Mamun

Mehmanparast

2021

Fatigue Fract Eng Mat Struct

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Thick weldments used in offshore structures frequently act as fatigue crack initiation sites due to stress concentration at weld toe as well as weld residual stress fields. This paper investigates the cyclic deformation behavior of S355 G10+M steel, which is predominantly used in offshore wind applications. Owing to the vast size difference of monopile structure and weld cross-section, a global-local finite element (FE) method was used, and the weld geometry was adopted from circumferential weld joints used in offshore wind turbine monopile foundations. Realistic service loads collected using supervisory control and data acquisition (SCADA) and wave buoy techniques were used in the FE model. A nonlinear isotropic-kinematic hardening model was calibrated using the strain controlled cyclic deformation results obtained from base metal (BM) as well as cross-weld specimen tests. The tests revealed that the S355 G10 +M BM and weld metal (WM) undergo continuous cyclic stress relaxation.Fatigue damage over a period of 20 years of operation was predicted using the local stress at the root of the weldments as the life limiting criterion. This study helps in quantifying the level of conservatism in the current monopile design approaches and has implications towards making wind energy more economic.

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Section: Resultscontrasting

confidence: 48%

On the performance of monopile weldments under service loading conditions and fatigue damage prediction

Biswal

Mamun

Mehmanparast

2021

Fatigue Fract Eng Mat Struct

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“…In many reports, [3][4][5][6][7][8][9][10] microstructure, mean stress, residual stress, mechanical properties and initial crack length were said to have large influence on the threshold and final failure regions. In addition, the accelerated region is said to be influenced by sample thickness.…”

Section: Introductionmentioning

confidence: 99%

The influence of microstructure on the fatigue crack growth rate in marine steels in the Paris Region

Igwemezie

2020

Fatigue Fract Eng Mat Struct

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This paper presents a study on the effect of microstructure on the fatigue crack growth (FCG) rate in advanced S355 marine steels in the Paris Region of the da/dN versus ΔK log–log plot. The environments of study were air and seawater (SW), under constant amplitude sinewave fatigue loading. Fundamentally, three phenomena (crack tip diversion, crack front bifurcation and metal crumb formation) were observed to influence the rate of FCG. These phenomena appear to be a function of the material microstructure, environment and crack tip loading conditions. The three factors retarded the crack growth by reducing or redistributing the effective driving force at the main active crack tip. A crack path containing extensively the three phenomena was observed to offer strong resistance to FCG. In SW, the degree of the electrochemical dissolution of the microplastic zone appears to be an additional primary factor influencing FCG in the steels.

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“…As depicted in Figure 6, there is a wide scatter in the fatigue crack growth rate in the threshold region for both the results predicted by the experiment and the FEA SMART© analysis tool. However, along the Paris' region, that is, after the threshold region, the test data points are seen to be dispersed around the best fit line of the experimental data such that it aligns in and can be represented by a straight line 54,65,71–79 . From the foregoing, it can be inferred that there is reasonable agreement between the test results and the FEA SMART© analysis results predicted.…”

Section: Resultsmentioning

confidence: 64%

Structural reliability assessment of offshore wind turbine support structures subjected to pitting corrosion‐fatigue: A damage tolerance modelling approach

et al. 2020

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The structural integrity of offshore wind turbine (OWT) support structures is affected by one of the most severe damage mechanisms known as pitting corrosion-fatigue. In this study, the structural reliability of such structures subjected to pitting corrosion-fatigue is assessed using a damage tolerance modelling approach. A probabilistic model that ascertains the reliability of the structure is presented, incorporating the randomness in cyclic load and corrosive environment as well as uncertainties in shape factor, pit size and aspect ratio. A non-intrusive formulation is proposed consisting of a sequence of steps. First, a stochastic parametric Finite Element Analysis (FEA) is performed using SMART© crack growth and Design Xplorer© facilities within the software package ANSYS. Secondly, the results obtained from the FEA are processed using an Artificial Neural Network (ANN) response surface modelling technique. Finally, the First Order Reliability Method (FORM) is used to calculate the reliability indices of components. The results reveal that for the inherent stochastic conditions, the structure becomes unsafe after the 18th year, before the attainment of the design life of 20 years. The FEA results are in very good agreement with results obtained from analysis steps outlined in design standard BS 7910 and other references designated as 'theoretical analysis methods' in this study. The results predict, for the case study, that the pit growth life is approximately 56% of the total pitting corrosion fatigue life. Sensitivity analysis results show that the aspect ratio of pits at critical size plays a significant role on the reliability of the structure.

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Residual stress measurements in offshore wind monopile weldments using neutron diffraction technique and contour method

Cited by 51 publications

References 22 publications

On the performance of monopile weldments under service loading conditions and fatigue damage prediction

On the performance of monopile weldments under service loading conditions and fatigue damage prediction

The influence of microstructure on the fatigue crack growth rate in marine steels in the Paris Region

Structural reliability assessment of offshore wind turbine support structures subjected to pitting corrosion‐fatigue: A damage tolerance modelling approach

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